This invention relates to a locking arrangement of a tape spool hub on a rotating shaft.
In the case of machines that use large spools of a magnetic tape wound onto a central hub, there exists the necessity that the spool itself be mounted in such a way that it seats firmly on the machine. This is especially necessary in the case of high rotating speeds and repeated accelerations and braking such as are found in continuous feeding automatic machines for the loading of magnetic tape onto a cassette.
One known locking arrangement uses a number of elastic balls that are brought in contact with the spool hub in such a way that the spool is held at least partially by the balls complementary positions. However, in this case, the spool or better the spool hub, when subjected to significant stress, has the tendency to jump out of the locking arrangement, causing a stop to production and possibly damage to the tape material on the spool.
In the case of other locking arrangements, ring elements made of plastic, or a type of rubber that is partially plastic are used. These ring elements can exercise a slight pressure on the hub resulting in locking, but provide low reliability and the probability of the hub jumping out, or falling off of the spool, and do not provide a high degree of reliability for a secured driving connection under continuous stress caused by various high speeds, quick starts and stops and other normal operating conditions.
An objective of the invention is to provide a reliable locking arrangement without the use of a mechanism having sharp edges, levers or similar means that are extremely dangerous at high speeds.
According to the invention, this objective is achieved by a locking arrangement of a tape spool hub on a rotating shaft which has a central body with a support base or support element that the hub and the shaft have in common. A mechanism for locking said hub with respect to the said support base comprises three operating elements made of plastic, that jointly project at the exterior of the central parts of three pivoted levers that rotate with the base or support element and which can be moved into frictional engagement with the spool by means of external control means operating on one end of the levers. Pivot pin arrangements for the levers are disposed under said support base or support element. Pivoting of the levers in response to the external control causes the three operating elements to be in a sloped position when they come in contact with the interior surface of said hub to not only frictionally drive the hub, but to also provide a force to retain the hub against the base or support element to avoid a jumping out or falling off of the hub.
These and other objects, features, and advantages of the present invention will become more apparent from the following description when taken with the accompanying drawings which show, for purposes of illustration only, an embodiment in accordance with the present invention.